Vehicle door latch

ABSTRACT

A vehicle door latch assembly including a pivotally mounted latch claw ( 10 ) having a mouth operatively co-acting with a striker as the door nears its closed position, a latching pawl ( 16 ) self-engaging with the claw to hold it in a latched condition retaining the door, and unlatching means selectively operable to disengage the latching pawl for opening the door: characterised in that the unlatching means comprises a pawl lifter ( 20 ) movable from a position of rest to carry the latching pawl out of engagement with the claw, a power output member ( 24 ) movable to engage and displace the pawl lifter from said position of rest, an input member ( 30 ) power actuated between first and second positions, clutch means ( 28,32 ) releasably drive connecting the input member to the output member to cause shifting of the latter as the input member moves to its second position, and an overriding element ( 36 ) carrying the clutch means into and out of drive connection, said overriding element being operatively coupled to the pawl to ensure that manual operation of the pawl lifter is not obstructed by failure or malfunction of power actuation of the input member.

BACKGROUND OF THE INVENTION

This invention relates to latches for vehicle doors, particularly forlight passenger and goods vehicles.

Powered locking and powered latching of doors is becoming more favored,both as part of central locking systems and to enable more effectiveweathersealing of doors and greater freedom in styling and design. Thereare advantages in providing for power actuated unlatching of doors. Forone, much of the mechanical linkage and components needed forconventional manual inside and outside door handles can be dispensed.Additionally, unitary lock and latch modules of standard form can bespeedily installed in doors of a wide range of vehicle models and typeswithout special adaptation.

SUMMARY OF THE INVENTION

The object of the invention is to provide improvements in vehicle doorlatch assemblies, in particular the provision of latches having a powerunlatching facility in an economical, effective and reliable form.

According to the invention, there is provided a vehicle door latchassembly including a pivotally mounted latch claw having a mouthoperatively co-acting with a striker as the door nears its closedposition, a latching pawl self-engaging with the claw to hold it in alatched condition retaining the door, and unlatching means selectivelyoperable to disengage the latching pawl for opening the door. Theunlatching means comprise a pawl lifter movable from a position of restto carry the latching pawl out of engagement with the claw, a poweroutput member movable to engage and displace the pawl lifter from saidposition of rest, an input member power actuated between first andsecond positions, clutch means releasably drive connecting the inputmember to the output member to cause shifting of the output member asthe input member moves to its second position, and an overriding elementcarrying the clutch means into and out of drive connection. Theoverriding element is operatively coupled to the pawl to ensure thatmanual operation of the pawl lifter is not obstructed by failure ormalfunction of power actuation of the input member.

Preferably a cam surface of the claw acts on the pawl when the claw isin the open position to operatively couple the overriding element andpawl.

According to a further aspect of the present invention, the overridingelement includes a surface acting in co-operation with a surface of theclaw to ensure that manual operation of the pawl lifter is notobstructed by failure or malfunction of power actuation of the inputmember.

The output member is conveniently a power release lever having an armpositioned for engagement with the pawl lifter and a second arm providedwith a drive formation forming a first element of the clutch means.

The input member may be a crank element coupled to an electric or otherpower actuator for angular movement and carrying a drive formationforming a second element of the clutch means, the pivot of the crankelement being carried on the overriding element which is shifted onmanual operation of the release means to move the crank element in adirection disengaging said drive formations of the clutch means.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of the invention is now more particularly described withreference to the accompanying drawings in which:

FIG. 1 is a diagram of power unlatching parts of a vehicle door latchassembly in an engaged rest position with some parts not relevant to theinvention removed for clarity,

FIG. 2 is a like diagram showing the parts during a power unlatchingoperation,

FIG. 3 is a like diagram with the parts in a power open position, and

FIG. 4 is a perspective view of the vehicle door latch assembly of FIG.1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1, the latch assembly, which will be operativelysecured in a door in a known manner, includes a conventional rotatinglatch claw having a mouth 12 for contacting with a striker operativelymounted to the associated door post. Claw 10 is biased by a claw springin a counter-clockwise direction. A pawl-tooth 16A of a latching pawl 16self engages with the claw 10 in a known manner to retain the claw 10,and hence the door, releaseably at a first safety position when the dooris near closed, and an inner position shown in FIG. 1 when the door isfully shut.

The assembly may include powered closing/latching of the door.

The unlatching means includes a pawl lifter 20 in the form of a leverpivoted co-axially with pawl 16 which engages the pawl 16 when angularlydisplaced from its position of rest as shown in FIG. 1, so causingdisengagzement of pawl 16 from claw 10 to free the door for opening.Manually operable release means acts on arm 20A of pawl lifter 20 via alock link to rotate pawl lifter 20 to unlatch the door.

An output member in the form of a power release lever 24, bestillustrated in FIG. 4, is fulcrummed on a fixed pivot whose axis isparallel to the claw axis. Its left-hand arm 26 is positioned to engagethe lower face of a righrward extension 20B of pawl lifter 20 so thatwhen it is turned clockwise it displaces lifter 20 and so causesdisengagement of pawl 16 independently of the manually operable releasemeans. The right hand arm of lever 24 terminates in a drive formation inthe form of a shoulder 28.

An input member in the form of a crank 30 includes a drive pin 32. Thecrank 30 extends alongside the righthand arm of the lever 24 and isengageable with the shoulder 28. Clockwise angular movement of the crank30 is transmitted to the level 24. An electric actuator motor is coupledto the crank 30 by a vertical power drive line 34, selectively operableto power crank 30.

Crank 30 is pivoted on the lower end of a swinging overriding element36, the upper end of which is mounted on a fixed pivot 38 in spacedparallel relationship to the axis of release lever 24. In the angularposition shown in FIGS. 1, 2 and 4 the pivot axes of crank 30 and lever24 are substantially co-incident, so maintaining the clutch meansconstituted by shoulder 28 and pin 32 in drive engagement.

The lower end of element 36 includes a camming formation 40 (FIG. 4)which co-acts with a ramp 42 on the pawl 16. If there is any malfunctionof the power unlatching actuator or associated parts, e.g. due to a flatbattery or the actuator jamming in an open, closed or intermediateposition, which might block the latching/unlatching functions, operationof the manually operable release means will result in counterclockwiserotation of pawl 16, causing ramp 42 to push formation 40 to the right.This displaces crank 30 to the right in relation to release lever 24,declutching pin 32 from shoulder 28 and freeing the release lever 24 sothat it cannot interfere with actuation of pawl lifter 20 by means ofthe manual operable release means.

A release lever spring on release lever 24 provides a force urgingcounterclockwise rotation of release lever 24 relative to overridingelement 36 to return the release lever 24 to the position shown in FIG.3.

A spring on overriding element 36 provides a restoring force urgingre-engagement of pin 32 and shoulder 28 when power actuation is restoredor reset.

FIG. 1 shows the latch in a closed position. Movement of the drive link34 vertically downwards causes clockwise rotation of release lever 24and counterclockwise rotation of pawl lifter 20 from an engaged position(see FIG. 1) to a first release position (see FIG. 2) resulting in thepawl 16 disengaging the claw notch.

The claw spring then rotates the claw 10 counterclockwise to an openposition (see FIG. 3) wherein a cam surface 10A of claw 10 contacts thepawl tooth 16A to rotate the pawl 16 further counter-clockwise to asecond release position (see FIG. 3). When the pawl 16 moves from thefirst release position, to the second release position the ramp 42pushes formation 40 to the right to disengage pin 32 from shoulder 28,wherein release lever 24 returns to its rest position under the actionof the release lever spring. Thus, even if the power actuator thenmalfunctions and remains in its release position as shown in FIG. 3, thedoor can still subsequently be correctly latched with full engagement ofthe pawl tooth 16A with the claw notch and also manually unlatched.

It should be noted that release of the clutch means is effectedindependently of the manually operable release means.

Also when the claw 10 is moved to its open position (either by manual orpower release) the release lever 24 will return to its rest position(see FIG. 3) independently from the subsequent operation of the manuallyoperable release means or the power actuator.

Thus manual operation of both door latching and unlatching is ensuredregardless of any failure or malfunction of the power unlatching eg thepower unlatching mechanism remaining in a latched, unlatched orintermediate condition.

The foregoing description is only exemplary of the principles of theinvention. Many modifications and variations of the present inventionare possible in light of the above teachings. The preferred embodimentsof this invention have been disclosed, however, so that one of ordinaryskill in the art would recognize that certain modifications would comewithin the scope of this invention. It is, therefore, to be understoodthat within the scope of the appended claims, the invention may bepracticed otherwise than as specially described. For that reason thefollowing claims should be studied to determine the true scope andcontent of this invention.

What is claimed is:
 1. A vehicle door latch assembly comprising: apivotally mounted latch claw having a mouth operatively co-acting with astriker as a vehicle door nears a closed position; a pawl self-engagingsaid claw to hold said claw in a latched condition retaining said door;and an unlatching mechanism selectively operable to disengage said pawlto open said door, said unlatching mechanism including: a pawl liftermovable from a rest position to carry said pawl out of engagement withsaid claw, an output member movable to engage and displace said pawllifter from said rest position, an input member actuatable by a poweractuator between a first position and a second position, said inputmember being releaseably drive connected to said output member to causeshifting of said output member as said input member moves to said secondposition, and an overriding element connected to said input member tomove said input member and said output member into and out of driveconnection and being operatively coupled to said pawl to maintain manualoperability of said pawl lifter if the power actuator fails to actuatethe input member.
 2. The latch assembly as recited in claim 1 whereinsaid output member is a power release lever mounted by a first pivot andincludes a first arm position for engagement with said pawl lifter and asecond arm provided with an output drive formation releaseably connectedto said input member.
 3. The latch assembly as recited in claim 1wherein said input member is a crank element mounted by a second pivotand includes an arm provided with an input drive formation releaseablyconnected to said output member.
 4. The latch assembly as recited inclaim 1 wherein said output member is a power release lever mounted by afirst pivot and includes a first arm position for engagement with saidpawl lifter and a second arm provided with an output drive formationreleaseably connected to said input member, and said input member is acrank element mounted by a second pivot and includes an arm providedwith an input drive formation releaseably connected to said outputmember.
 5. The latch assembly as defined in claim 4 wherein said secondarm of said release lever and said arm of said crank element are ingenerally face to face relationship, and said input drive formation andsaid output drive formation co-act.
 6. The latch assembly as recited inclaim 4 wherein said input drive formation is a pin and said outputdrive formation is a notch.
 7. The latch assembly as recited in claim 4wherein said output drive formation is a pin and said input driveformation is a notch.
 8. The latch assembly as recited in claim 4wherein said second pivot is displaceable to shift said crank element toengage and disengage said input drive formation and said output driveformation.
 9. The latch assembly as recited in claim 4 wherein saidsecond pivot is mounted on said overriding element.
 10. The latchassembly as recited in claim 4 wherein said overriding element is a linkmounted by a third pivot.
 11. The latch assembly as recited in claim 4wherein said overriding element is shifted on manual operation of saidunlatching mechanism to move said crank element in a directiondisengaging said input drive formation and said output drive formation.12. The latch assembly as recited in claim 4 wherein said overridingelement is operatively acted on by said pawl through a camming formationon said overriding element.
 13. The latch assembly as recited in claim 4wherein said overriding element is operatively acted on by said pawlthrough a camming formation on a portion of said pawl contacted by saidoverriding element.
 14. The latch assembly as recited in claim 4 whereinsaid overriding element is resiliently biased to engage said input driveformation and said output drive formation.
 15. The latch assembly asrecited in claim 1 wherein said claw includes a cam surface which actson said pawl when said claw is in said open position to operativelycouple said overriding element and said pawl.
 16. A vehicle door latchassembly including: a pivotally mounted latch claw having a mouthoperatively co-acting with a striker as a vehicle door nears a closedposition; a latching pawl self-engaging said claw to hold said claw in alatched condition retaining said door; and an unlatching mechanismselectively operable to disengage said pawl to open said door including:a pawl lifter movable from a rest position to carry said pawl out ofengagement with said claw, an output member movable to engage anddisplace said pawl lifter from said rest position, an input memberactuatable by a power actuator between a first position and a secondposition, said input member being releaseably drive connected to saidoutput member to cause shifting of said output member as said inputmember moves to said second position, and an overriding elementconnected to said input member to move said input member and said outputmember into and out of drive connection including a surface acting inco-operation with a surface of said claw to maintain manual operabilityof said pawl lifter if the power actuator fails to actuate said inputmember.